Detection and characterization of QoI resistance inPyrenophora tritici‐repentispopulations causing tan spot of wheat in Argentina

Abstract

Wheat is the most important cereal crop in Argentina, with a cultivated area of about 6,800,000 hectares, a total production of 16.3 million tonnes, and an average yield of 3,000 kg/ha in the 2019/2020 growing season (MINAGRI, 2021). However, its production is limited by the presence of several diseases. The most important include stripe rust (Puccinia striiformis f. sp. tritici), leaf rust (P. triticina), stem rust (P. graminis f. sp. tritici), tan spot (Pyrenophora tritici-repentis, Ptr), and Septoria tritici blotch (STB; Zymoseptoria tritici).During the last 25 years, Ptr populations have become prevalent in all wheat-growing regions of Argentina, causing yield losses estimated at 10%-20% (Annone, 1998). The disease began to significantly affect wheat crops in the north-central region of the Buenos Aires province in the early 1980s (Annone, 1985). Since then, occurrence of tan spot has been of such magnitude that it rapidly replaced STB in prevalence, incidence, and severity (Annone, 1990). There are several causes that could explain the increase in the importance of tan spot in Argentinian wheat-growing regions in recent years.Among them, the following can be highlighted (Carmona et al., 1999,

Resistance of Black Aspergilli Species from Grape Vineyards to SDHI, QoI, DMI, and Phenylpyrrole Fungicides

“…In detail, the occurrence of an intron directly after codon 143 might have a significant impact on the splicing process, resulting in cytochrome b deficiency, and organisms with these alterations would not survive [ 48 , 49 ]. In addition to G143A, the replacement of phenylalanine by leucine at codon 129 (F129L) or the replacement of glycine by arginine at position 137 (G137R) have been reported in a limited number of pathogenic plant species such as Alternaria solani , Passalora fulva , or Pyrenophora tritici-repentis [ 50 , 51 ], but both are associated with relatively low levels of resistance to QoIs. Resistance to QoIs in A. uvarum strains, isolated from grapes, has very recently been reported in the mid-Atlantic U.S. [ 24 ].…”

Differential response to DMI, QoI and SDHI fungicides in wheat and signal grass blast populations from Minas Gerais, Brazil

“…Direct comparison of the EC 50 data between our study and those previous works may be limited due to differences in methodology because we used the FRAC‐recommended method, the conidial germination assay (Russell, 2004), and those authors used a mycelial growth assay. Several authors discuss that the conidial germination method is more appropriate to determine the sensitivity to QoIs (Olaya et al, 1998; Pethybridge et al, 2020; Russell, 2004; Sautua & Carmona, 2021; Teramoto et al, 2017).…”

Comprehensive Overview of β-Methoxyacrylate Derivatives as Cytochrome bc1 Inhibitors for Novel Pesticide Discovery

“…However, due to the single target and continuous unreasonable application, resistance has become the main limitation for β-methoxyacrylate fungicides. Resistance to β-methoxyacrylate fungicides is usually caused by a single amino acid substitution from glycine to alanine (G143A) or from phenylalanine to leucine (F129L), which have been detected in various pathogens. − The G143A mutation is not involved in enzyme activity, whereas the F129L is closer to the heme and is potentially involved in electron transfer. On the other hand, inhibition of electron transfer by Qo inhibitors leads to the increase of intracellular reactive oxygen species (ROS), which can induce the expression of alternative oxidase (AOX) and subsequently activate the alternative oxidation pathway of mitochondria, resulting in fungicide resistance.…”